Featured Research

from universities, journals, and other organizations

Grasshoppers frightened by spiders affect whole ecosystem

Date:

June 14, 2012

Source:

Hebrew University of Jerusalem

Summary:

Grasshoppers ‘stressed’ by spiders affect the productivity of our soil. A grasshopper who is in fear of an attacker, such as a spider, will enter a situation of stress and will consume a greater quantity of carbohydrate-rich plants -- similar to humans under stress who might eat more sweets.

Related Articles

How do grasshoppers who are being frightened by spiders affect our ecosystem? In no small measure, say researchers at the Hebrew University of Jerusalem and at Yale University in the US.

A grasshopper who is in fear of an attacker, such as a spider, will enter a situation of stress and will consume a greater quantity of carbohydrate-rich plants -- similar to humans under stress who might eat more sweets.

This type of reaction will, in turn, cause chemical changes in the grasshopper and in its excretions, affecting the ecosystem it inhabits. How does this happen?

When the scared grasshopper dies, its carcass, now containing less nitrogen as a result of its diet change, will have an effect on the microbes in the ground, which are responsible for breaking down animals and plants.

With less nitrogen available, the microbes will be decomposing the hard-to-break-down plant materials in the soil at a slower rate. Thus, the fear of predation may slow down degradation of complex organic materials to the simpler compounds required for plant growth.

Research on this biological-ecological phenomenon was carried out by Dr. Dror Halwena of the Department of Ecology, Evolution and Behavior at the Alexander Silberman Institute of Life Sciences at the Hebrew University of Jerusalem, in cooperation with researchers at Yale University in the United States. An article on their research appears in the current edition of the journal Science.

In their research, the scientists exposed grasshoppers to spiders in order to arouse the stress reaction. They also used a control group of non-stressed grasshoppers. The scared grasshoppers had a higher carbon-to-nitrogen ratio in their bodies than non-scared grasshoppers.

In further laboratory and field tests, the researchers tested the influence of remains of grasshoppers from the two groups on soil. After the microbes consumed the grasshopper remains, the researchers added plants to the surface. In the experiments, it was shown that the decomposition rate of the plants in the areas in which the stress-free grasshopper remains were introduced decomposed at a rate between 62 and 200 percent faster than in the samples in which the stressed grasshopper s were put.

In a further experiment, the researchers used "artificial grasshoppers" -- a mixture of sugar, protein, and chitin (the organic compound found in the grasshopper external skeleton) -- in varying quantities. Here, too, they found that even a small amount of nitrogen (found in the protein) added to the soil increases significantly the functioning of the microbes responsible for breaking down the organic matter in plants.

"We are dealing here with an absolutely new kind of mechanism whereby every small chemical change in a creature can regulate the natural cycle, thus in effect affecting the ecology in total, such as the amount of carbon dioxide released into the atmosphere (through decomposition) and field crop productivity. This has tremendous consequences for our ecological understanding of the living world," said Dr. Halwena.

"We are gaining a greater understanding of the necessity of conserving all of the component parts of the ecosystem in general and of predators in particular. We are losing predators in nature at a much faster rate than other species," Dr. Halwena commented.

He also viewed the research as a vehicle that will enable scientists to better predict changes in the biological system as a result of such human-induced phenomenon as overfishing, hunting or global warming that can undermine the entire ecosystem.

More From ScienceDaily

More Plants & Animals News

Featured Research

Mar. 3, 2015 — New assays can detect malaria parasites in human blood at very low levels and might be helpful in the campaign to eradicate malaria, reports a new study. An international team led by Ingrid Felger, ... full story

Mar. 3, 2015 — While studying a ground-nesting bird population near El Reno, Okla., a research team found that stress during a severe weather outbreak of May 31, 2013, had manifested itself into malformations in ... full story

Mar. 3, 2015 — The 3-D printing scene, a growing favorite of do-it-yourselfers, has spread to the study of plasma physics. With a series of experiments, researchers have found that 3-D printers can be an important ... full story

Mar. 3, 2015 — Most people consume more salt than they need and therefore have a higher risk of heart disease and stroke, which are the two leading causes of death worldwide. But a new study reveals that dietary ... full story

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Pediatric otolaryngologists and surgeons are concerned with parents getting the wrong message regarding the safety/desirability of letting babies and young children eat peanuts to prevent them from ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Similar to humans and animals, plants possess an innate immune system that protects them from invading pathogens. Molecular structures that only occur in pathogens enable their recognition and ... full story

Mar. 3, 2015 — For almost a century, scientists have been puzzled by a process that is crucial to much of the life in Earth's oceans: Why does calcium carbonate, the tough material of seashells and corals, ... full story

Featured Videos

Rare Goblin Shark Found in Australia

AFP (Mar. 3, 2015) — A goblin shark, a rare sea creature described as an &apos;alien of the deep&apos; is found off Australia and delivered to the Australian Museum in Sydney. Duration: 01:25
Video provided by AFP

Zookeepers Copy Animal Poses In Hilarious Viral Photos

Buzz60 (Mar. 2, 2015) — Zookeepers at the Symbio Wildlife Park in Helensburgh, Australia decided to take some of their favorite animal photos and recreate them by posing just like the animals. Jen Markham (@jenmarkham) has the story.
Video provided by Buzz60

Related Stories

Dec. 18, 2013 — Spiders may not be the pure predators we generally believe, after a study found that some make up a quarter of their diet by eating pollen. Biologists have now demonstrated that orb web spiders -- ... full story

June 17, 2013 — A new study shows that the predator-prey relationship can affect the flow of carbon through an ecosystem. This previously unmeasured influence on the environment may offer a new way of looking at ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.